We intend to concentrate during the coming year on factors affecting the selection, formulation, and execution of population policies. To do this, we shall give high priority to the study of how the changing system of international relations, combined with world demographic and technological changes, has affected population policies since 1900. However, since policy is not only influenced by such objected factors but also by theories and beliefs concerning causal relationships, we shall deal with the validity and invalidity of subjective ideas as well. Some of these are biological, holding that given policies will affect human genetics or health; others are social or economic, holding that certain policies will affect investment, employment, or what not. We shall select important theories--beliefs about the effects of population policy and analyze their empirical validity or invalidity. Four topics for consideration along this line will be the biological effets of change in the age and spacing of childbearing, the social and economic effects of older age structures, the educational effects of fertility reduction and distributional change, and the national power effects of population growth or decline. Our syntheses of these studies will be both at the international and at the local regional level.